Section 3-1Cell Size:

• Magnification: quality of making an image appear larger than actual size• Resolution: measure of clarity of an

image• e- microscopes have ↑

mag/resolution

Section 3-1Light microscopes:

•Form an image when light passes through 1 or more lenses to produce an enlarged image of specimen

Section 3-1Types of Microscopes:

• Electron microscopes use beam of e- rather than light to view specimen• Live organisms can’t be viewed w/

e- microscope

Section 3-1Transmission Electron

Microscope:• e- beam directed at very thin slice of

specimen stained w/metal ions • e- that pass through strike

fluorescent screen, forming an image; can’t view live specimen

Section 3-1Scanning Electron Microscope:

• e- beam is focused on specimen coated w/ very thin layer of metal • Shows 3D details of surface of

specimen; can’t view live specimenNeutrophil (yellow) engulfing anthrax (orange)

Section 3-1Scanning Tunneling Microscope:

• Needle-like probe measures differences in voltage caused by e- that leak, or tunnel, from surface of object being viewed • Shows 3D details of surface of

specimen • Live specimens can be viewede- surrounded by 48 iron atoms

Section 3-2Cell Size

•Small cells function more efficiently than large cells •If cell’s surface area–to-volume ratio is too low, subs can’t enter/leave cell well enough to meet cell’s needs

Section 3-2Cell Theory has 3 parts:

1. All LT are made of 1 or more cells2. Cells are basic units of

structure/function in organisms3. All cells arise from existing cells

All cells have: • Cell membrane• Cytoplasm • Cytoskeleton • DNA • Ribosome

Section 3-2Prokaryotic cells (bacteria):

•Single-celled organisms; no nucleus or internal compartments •Have cell wall, may have cilia/flagella•Have circular molecule of DNAE. coli bacteria cell

Section 3-2

Eukaryotic cells (all other LT):•Nucleus contains cell’s DNA•Other internal compartments, organelles

Typical animal cell

Section 3-2Cell membrane:

• Selectively permeable membrane, determines which substances enter/leave cell

• Selective permeability caused by the way phospholipids interact w/ water

• Phospholipid made of phosphate group and 2 fatty acids

Section 3-2Proteins are embedded in the

phospholipid bilayer to help move substances across cell membrane

“Inside of the cell”

“Outside of the cell”

Section 3-3Nucleus:

•Internal compartment stores cell’s DNA •Nucleus controls cell’s functions•Nuclear envelope is double membrane surrounding the nucleus•Nuclear pores are small openings scattered over surface of nuclear envelope

Section 3-3Ribosome:

•Structure where proteins are madeEndoplasmic Reticulum (ER): •Extensive network of internal membranes that move proteins and other subs through cell; acts as a highway

Section 3-3Vesicles:

•Carry newly made proteins through cytoplasm from ER to Golgi apparatusGolgi apparatus: •Set of flattened, membrane-bound sacs that serve as packaging/distribution center of cell

Section 3-3Lysosome:

•Sacs of enzymes that engulf/breakdown large substances into smaller onesMitochondria: (aka “powerhouse”) •Organelles that convert food energy from organic compounds to make ATPATP: •Main energy currency of cell; “spendable”

Section 3-3Plants have 3 structures not found in

animal cells:1. Cell Wall: support/maintain shape of cell; protects cells, connect cell to adjacent cells 2. Chloroplasts: uses light energy to make organic compds from CO2/water3. Large Central Vacuole: stores water, nutrients, wastes

Section 3-3Summary of Organelles: